photo: Todd Woody

Green Wombat has been in transition so I’m a bit behind on posting. In case you missed it, in the Sunday New York Times on May 9, I wrote a profile of David Gelbaum, one of the nation’s biggest — and until now — most reclusive green technology investors and environmental philanthropists:

AMID the $6 million homes perched on a beachfront cliff in this conservative Southern California enclave, the seven-year-old Honda Civic hybrid with the Obama bumper sticker is the giveaway.

It’s not the usual drive of choice for wealthy former hedge fund managers like David Gelbaum. Then again, there’s not much that is business as usual about Mr. Gelbaum, an intensely private person who happens to be one of the nation’s largest — and largely unknown — green technology investors and environmental philanthropists.

Mr. Gelbaum has invested $500 million in clean-tech companies since 2002 through his Quercus Trust, amassing a portfolio of some 40 businesses involved in nearly every aspect of the emerging green economy, be it renewable energy, the smart electric grid, sustainable agriculture, electric cars or biological remediation of oil spills. He has poured almost as much into environmental causes.

“I think his impact on green technology is huge,” says Bill Gross, the serial technology entrepreneur and founder of eSolar, a solar power start-up in which Mr. Gelbaum has invested. “He is supporting bolder and riskier bets, and he’s doing it from a different filter than a traditional venture capitalist, and I think that makes a wider opportunity for success.”

In this economic downturn, many venture capitalists have grown cautious about putting money into what Vinod Khosla, the prominent Silicon Valley green tech investor, calls “science experiments.” But Quercus Trust is still taking chances on blue-sky start-ups pursuing technological breakthroughs.

Working outside the clubby venture capital network, Mr. Gelbaum has, until recently, maintained an obsessively low profile. In Silicon Valley, he remains something of an unknown. Associates say his near-invisibility is owed to a genuine modesty and concerns over the security of his family because of his wealth. Recipients of his philanthropy, for instance, signed confidentiality agreements that forbade mention of his name.

Mr. Gelbaum says he decided to break his long silence upon becoming chief executive in February of Entech Solar, one of his portfolio companies that is publicly traded. “This is what’s best for the company,” he says, pointing out that Entech benefits if he maintains a more public profile.

It is too early to predict whether Mr. Gelbaum’s big green bets will pay off. But he’s been capitalizing on two trends: the rapid decline in the price of photovoltaic power, and a focus on cutting capital costs as solar power competition with China intensifies.

His environmental philanthropy also gives him an influence beyond laboratories and boardrooms. He has given $200 million to the Sierra Club and $250 million to the Wildlands Conservancy, a land trust he co-founded that has acquired and preserved 1,200 square miles of land in California, including more than a half million acres of the Mojave Desert.

About Green Wombat

Green Wombat is written by
Todd Woody, a veteran environmental journalist based in California who writes for The New York Times, the Los Angeles Times, Grist and Yale e360. He's one of the few people on the planet who have held a northern hairy-nosed wombat in the wild.

Todd formerly was a senior editor at Fortune magazine, an assistant managing editor at Business 2.0 magazine and the business editor of the San Jose Mercury News.